Lid Made of Paper and Method for its Manufacture

ABSTRACT

A lid made of paper and a method for its manufacture, comprising a lid disk and a lid ring having a longitudinal axis and a circumferential wall extending in the direction of the longitudinal axis and having an inner surface and an outer surface as well as a first end and a second end. The outer circumference of the lid ring has a U-shaped region with a first wall section and a second wall section, which are connected to one another via a third wall section. The lid ring has a U-shaped region with a first wall section and a second wall section connected to each other via a third wall section. The lid ring engages with its first end in the U-shaped region of the lid disk such that the first wall section rests against the inner surface and the second wall section rests against the outer surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of DE 102020103806.2 filed on 2020 Feb. 13; this application is incorporated by reference herein in its entirety.

BACKGROUND

The invention relates to a lid made of paper and a method for its manufacture according to the preamble of the first and fifth claim.

For example, DE 830891 B already discloses two-part lids made of paper having a first paper element, which represents the circumferential lateral edge extending largely vertically, and having a second paper element, which represents an inner horizontally extending lid closure, and having a third paper element, which represents an outer horizontally extending lid closure.

This structure is relatively complex and the method of manufacture is complicated.

SUMMARY

The invention relates to a lid (D) made of paper and a method for its manufacture, consisting of a lid disk (1) and a lid ring (2) having a longitudinal axis (L2) and a circumferential wall (3) extending in the direction of the longitudinal axis (L2) and having an inner surface (3A) and an outer surface (3B) as well as a first end (3C) and a second end (3D), wherein the outer circumference of the lid ring (2) has a U-shaped region (1.2) with a first wall section (1.3) and a second wall section (1.4), which are connected to one another via a third wall section (1.5), and wherein the lid ring (2) has a U-shaped region (1.4) with a first wall section (1.3) and a second wall section (1.4).4) connected to each other via a third wall section (1.5), and wherein the lid ring (2) engages with its first end (3C) in the U-shaped region (1.2) of the lid disk (1) such that the first wall section (1.3) rests against the inner surface (3A) and the second wall section (1.4) rests against the outer surface (3B), and in that the first wall section (1.3) and the second wall section (1.4) of the U-shaped region (1.2) of the lid disk are connected to the first end (3 c) of the lid ring (2) by a material bond. According to the method, first a pre-drawn conical lid disk (2) is produced, which has an edge region (4) and a flat region (1.1) offset relative thereto by a conical shoulder (5), that a lid ring (2) is positioned at the conical shoulder (5) and that subsequently at least one region of the conical shoulder (5) is formed against an inner surface 3A and the edge region (4) is formed against an outer surface (3B) of the wall (3) of the lid ring (1) and sealed to the latter. (FIG. 5)

DETAILED DESCRIPTION

It is the object of the invention to develop a lid made of paper which can be produced simply and inexpensively from two parts with a corresponding method using a device and which has sufficient stability to close a container several times and is stackable in one embodiment.

This object is solved with the features of the independent claims.

Advantageous embodiments result from the subclaims.

The lid according to the invention consists of paper and/or paper composite and comprises a lid disk and a lid ring having a longitudinal axis and a circumferential wall extending in the direction of the longitudinal axis and having an inner surface and an outer surface as well as a first end and a second end, wherein the lid disk and the lid ring are connected to one another in a materially bonded manner and wherein the lid disk has a flat region extending transversely to the longitudinal axis, which engages in the lid ring and, on its outer circumference, a U-shaped region adjoining the flat region and having a first wall section and a second wall section, which are connected to one another via a third wall section, and wherein the lid ring engages with its first end in the U-shaped region of the lid disk in such a way that the first wall section rests against the inner surface and the second wall section rests against the outer surface, and that the first wall section and the second wall section of the U-shaped region of the lid disk are connected in a materially bonded manner to the first end of the lid ring.

The wall of the lid ring can be drawn inwards/in the direction towards the longitudinal axis in its region which engages in the U-shaped region of the lid disk, so that a shoulder is preferably formed below the lid disk, in order to produce stackability.

For stackability, the outer diameter of the lid disk is smaller than the inner diameter of the wall of the lid ring in the area of the open second end facing away from the lid ring.

During stacking, the inner diameter of a lid then engages over the outer diameter of a lid below it in the area of the lid disk, and the open second end rests on the shoulder of the lid below it.

In the method for producing the lid according to the invention, first a pre-drawn conical lid disk is produced which has an edge region and a flat region offset therefrom by a conical shoulder, and wherein a lid ring is positioned with a first end of its wall on the outer circumference of the conical shoulder or inside the conical shoulder, and then at least one region of the conical shoulder is molded against an inner surface and the edge region is molded against an outer surface of the wall of the lid ring and is joined to the latter by means of material bonding.

The wall of the lid ring may be retracted in the direction of the longitudinal axis of the lid ring to provide stackability of the lid when joined to the lid disk. Alternatively, the wall of the lid ring may be retracted at a first end in the direction of the longitudinal axis prior to joining to the lid disk. As a further alternative, the wall of the lid ring may also be retracted at a first end in the direction towards the longitudinal axis after connection to the lid disk.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference to an exemplary embodiment and associated drawings, wherein:

FIG. 1 shows an initial part for the preformed lid disk,

FIG. 2 shows a preformed/advanced lid disk,

FIG. 3 shows a lid ring,

FIG. 4 shows a lid disk positioned on the lid ring,

FIG. 5 shows a stackable lid made of lid disk and lid ring in longitudinal section,

FIG. 6 shows a detail X according to FIG. 5,

FIG. 7 shows several lids stacked on top of each other according to FIG. 5,

FIG. 8 shows a longitudinal section of a non-stackable lid,

FIG. 9 shows a lid disk and lid ring inserted into a tool,

FIG. 10 shows a tool after joining/sealing of lid disk and lid ring,

FIG. 11 shows a variant of producing the indent on the lid ring before connecting to the lid disk,

FIG. 12 shows a schematic representation of the connection between the lid disk and the lid ring with a previously generated indent on the lid ring,

FIG. 13 shows a three-dimensional representation of a lid according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the initial part 1′ of a lid disk, which consists of a flat paper section or cardboard cut to the shape of the lid. In plan view, the initial part can be round, oval, kidney-shaped or otherwise shaped, depending on the desired shape of the lid. On its underside 1 a, the initial part 1′ has a coating suitable for producing a material bond, preferably in the form of a sealing medium, in particular a sealing layer or sealing film, which is not shown here, however. The sealing medium can, for example, be laminated, extruded or applied as a sealing lacquer. It consists, for example, of PE (polyethylene).

A barrier layer (not shown) can be arranged between the sealing medium and the underside 1 a of the lid disk (e.g. in the form of a ceramic coating or made of aluminum foil, PET (polyethylene terephthalate) or EVOH (ethylene-vinyl alcohol copolymer).

The conically protruding lid disk 1 in sectional view is shown in FIG. 2. This has an edge region 4 on the outer circumference and a substantially flat region 1.1 offset from it by a conical shoulder 5. This can be flat, as shown here, or curved in the direction of the edge or in the opposite direction thereto. Furthermore, the substantially planar area may contain one or more beads (not shown).

The lid ring 2 shown in FIG. 3 was preferably made of paper by a winding process and in particular spirally wound. The lid ring 2 has a circumferentially closed wall 3, the course of which is adapted to the shape of the cover to be produced and thus to the lid disk 1 (e.g. round, oval, kidney-shaped, etc.). The lid ring 2 has a longitudinal axis L2 and an inside diameter d2.

The wall 3 has an inner surface 3A and an outer surface 3B, and a first end 3C and an opposite second end 3D.

In addition or as an alternative to the lid disk 1 with sealing medium, the inner surface 3A and/or the outer surface 3B of the lid ring 2 can also be provided with sealing medium, as described for the lid disk 1, at least in the area of connection with the lid disk 1, and may also have a barrier layer.

To establish the connection between lid disk 1 and lid ring 2, the lid ring 1 is placed on the first end 3C of the cover sleeve 2 (see FIG. 4). Advantageously, the conical shoulder 5 serves to center the cover sleeve 2 or the lid disk 1 to the lid ring 2.

Now, by means of appropriate tools not shown, the upper unmarked area of the wall 3 of the cover sleeve 2 is formed radially inwards in the direction of the longitudinal axis L2 (indicated by the arrows facing inwards) and the edge region 4 of the lid disk 1 is bent downwards (indicated by the arrows facing downwards). In this process, the edge region 4 of the cover sleeve 1 is pressed against the outer surface 3B and the conical shoulder 5 of the cover sleeve 1 is pressed against the inner surface 3A of the cover sleeve 2, and the material bond is produced under pressure and heat, in particular by sealing, between the lid disk 1 and the lid ring 2. The temperature required for sealing is usually between 100° C. and 350° C. depending on the sealing medium and, for example, between 120° C. and 200° C. for PE as the sealing medium.

After forming and producing the material bond, the lid D is finished and the lid disk 1 has a U-shaped region 1.2 at the edge (see FIGS. 5 and 6), in which the wall 3 of the lid ring 2 engages, wherein the wall 3 is materially bonded to the U-shaped region 1.2 at its inner surface 3A and at its outer surface 3B. In the region of the lid disk 1, the lid D has a cup-like recess 6.1 with a depth t1 and an inside diameter d1.

In the area of the lid disk 1, the lid D has an outer diameter D1.

The wall 3 has an inner diameter d2 after the shoulder 3.1 up to the second end 3D.

From the detail according to FIG. 6, it can be seen that the U-shaped region 1.1 adjoining the substantially flat region 1.1 has an inner first wall section 1.3 (leg) which is joined to the inner surface 3A of the wall of the lid ring 2, and that a second wall section 1.4 (leg) is joined to the outer surface 3B of the wall 3 of the lid ring 2 in a materially bonded manner (preferably by sealing). The first and second wall sections 1.3, 1.4 of the lid disk 1 and the end 3C of the wall 3 of the lid ring 2 located therebetween are oriented substantially parallel to the longitudinal axis L2 of the lid ring 2, wherein the first and second wall sections 1.3, 1.4 extend substantially rectilinearly.

The first wall section 1.3 and the second wall section 1.4 of the U-shaped area 1.2 of the lid disk 1 are connected to each other via a third wall section 1.5.

The wall 3 is retracted radially inwards/in the direction of the longitudinal axis L2 at the end 3C that engages the U-shaped region 1.2 of the lid disk 1, forming a shoulder 3.1 below the second wall section 1.4 of the U-shaped region.

The inner diameter d2 of the wall 3 from the shoulder 3.1 to the second end 3D is slightly larger than the outer diameter D1 in the area of the lid disk 1, so that for stacking the inner diameter d2 of a lid D can be slipped over the outer diameter D1 of the lid disk 1 of another lid D. The second end 3D of a lid D then rests on the shoulder 3.1 of the other lid D.

The wall 3 of the lid sleeve 2 has an outer diameter D2 from the shoulder 3.1 to the second end 3D.

FIG. 7 shows an example of four lids D stacked one on top of the other in longitudinal section. The upper lid D engages in each case with its inner diameter d2 of the lower region of the lid sleeve 2 over the outer diameter D1 of the second wall section of the U-shaped region, which is not designated here, and thus the outer diameter D1 of the lid disk 1.

FIG. 8 shows a lid D according to the invention which is not stackable. This also has a lid disk 1 with a substantially flat region 1.1 and an externally adjoining U-shaped region 1.1 with an inner first wall section 1.3 (leg), which is connected to the inner surface 3A of the wall 3 of the lid ring 2, and a second wall section 1.4 (leg), which is connected in a materially bonded manner to the outer surface 3B of the wall 3 of the lid ring 2 (preferably by sealing). The first and second wall sections 1.3, 1.4 of the lid disk 1 and the end 3C of the wall 3 of the lid ring 2 located therebetween are also oriented here substantially parallel to the longitudinal axis L2 of the lid ring 2, wherein the first and second wall sections 1.3, 1.4 extend substantially in a straight line. The first wall section 1.3 and the second wall section 1.4 of the U-shaped region 1.2 of the lid disk 1 are connected to each other via a third wall section 1.5. The wall 3 of the lid ring 2 extends rectilinearly and parallel to the longitudinal axis L2 over the entire length of the lid ring.

In both embodiment variants—stackable and non-stackable—the lid D according to the invention thus consists of two parts in the form of lid disk 1 and lid ring 2, which are connected to one another by a material bond. The straight connection areas between lid disk 1 and lid ring 2 create a lid D that extends essentially in a straight line.

The method for producing a stackable lid using the appropriate tools will be explained below by way of example.

Firstly, a protruding conical lid disk 2 is produced which has an edge region 4 and a flat region 1.1 offset by a conical shoulder 5.

As shown in FIG. 9, the lid ring 2 is positioned with its inner diameter d2 on the undesignated outer diameter of a lower die 6, so that the first end 3C of the wall 3 of the lid ring 2 projects by a length L beyond a radially inwardly pointing shoulder 6.1 of the lower die 6. Now the advanced conical lid ring 1 is placed with the underside of its edge region 4 on the first end 3C of the wall 3 and positioned here on the outer circumference of the conical shoulder 5.

An upper die 7 now moves downward and holds the lid ring 1 by fixing it in the radius between the conical shoulder 5 and the flat region 1.1 with a circumferential edge 7.1 against the radially inner end of the shoulder 6.1 of the lower die 6. The upper die 7 has an outer diameter D7 which corresponds to the subsequent inner diameter d1 of the lid disk 1 of the finished lid D.

Now a ring punch 8 moves from the direction of the upper die 7 in the direction of the lower die 6.

In the direction of the lower die 6, the ring punch 8 has an inner diameter 8 d 2 which corresponds to the outer diameter D2 of the lid ring 2 or is slightly larger. The diameter 8 d 2 is adjoined by a radially inward slope 8.1 which extends essentially parallel to the shoulder 6.1 of the lower die 6. The slope is adjoined by an inside diameter 8 d 1 which corresponds approximately to the outside diameter D1 of the finished lid D in the area of the lid disk 1.

The die is heated at least in the area of the joining zone between lid disk 1 and lid ring 2, but this is not shown.

The final position of the ring punch 8 is shown in FIG. 10. During its stroke movement in the direction of the lower die, the edge region 4 of the lid disk 1 was formed downward and pressed against the outer diameter of the lid ring 2. As a result of the slope 8.1 and the subsequent smaller inside diameter 8 d 1 of the ring punch 8, the upper region 3 c of the lid ring 2, the adjacent edge region 4 and the conical region 5 of the lid disk 2 were pressed radially inward against the outside diameter D7 of the upper die 7.

The pressure and the sealing temperature (preferably between 120° C. and 300° C.) produce a material bond between the lid disk 1 and the lid ring 2 in the region in which the first end 3C of the wall 3 of the lid ring is now located between the wall regions 1.3 and 1.4 of the lid disk 1. The undesignated gap formed between the outer diameter D7 and the inner diameter 8 d 1 is slightly less than the sum of the thicknesses of the wall regions 1.3, 1.4 of the lid disk 2 and the wall 3 of the lid ring 2 located therebetween, as a result of which the pressure is built up by their compression.

After the sealing process has been completed, the ring punch 8 moves upwards, the lower die 6 and the upper die 7 are opened and the lid is ejected by means of an ejector not shown.

It is also possible to make the indent of the first end 3C of the wall 3 of the lid ring 2 before or after the connection with the lid disk.

This is carried out, for example, as indicated in FIG. 11, by rolling displacement of the wall 3 between an outer roller 9 (or an outer rail) and an inner roller 10. These have a mutually corresponding contour corresponding to the wall indent to be produced. The advantage here is that this process can also be used to simultaneously produce a circumferential bead in the wall area of the lid sleeve, which is present in a large number of lids.

According to FIG. 12, the edge region 4 and the conical region 5 of the lid disk 1 are then also formed against and sealed to the radially inwardly formed area of the wall of the lid ring 2.

A stackable lid D according to the invention is shown in FIG. 13. This is closed at the top by the lid disk 1, which is materially bonded to the lid ring 2. The outer diameter D1 in the region of the lid disk 1 is smaller than the outer diameter D2 in the region of the lid ring 2, thus forming a shoulder 3.1.

The inner diameter of the lid D, which is not designated here, reaches over the outer diameter D1 for stacking.

LIST OF REFERENCE NUMERALS

-   1′ Initial part -   1 a Underside -   1 Lid disk -   1.1 Flat region -   1.2 U-shaped region -   1.3 First wall section -   1.4 Second wall section -   1.5 Third wall section -   1.6 Depression -   2 Lid ring -   3 Wall -   3A Inner surface -   3B Outer surface -   3C First end -   3D Second end -   3.1 Shoulder -   4 Edge area -   5 Conical shoulder of lid ring -   6 Lower die -   6.1 Shoulder of lower die -   7 Upper die -   7.1 Peripheral edge -   8 Ring punch -   8.1 Slope -   8 d 1 Internal diameter of ring punch -   8 d 2 Internal diameter of ring punch -   9 Outer roller -   10 Inner roller -   d1 Internal diameter of lid disk -   d2 Internal diameter of lid ring/wall -   t1 Depth -   D Lid -   D1 Outside diameter of lid disk -   D7 Outer diameter of upper die -   L Length -   L2 Longitudinal axis 

1. A lid (D) made of paper, comprising a lid disk (1) and a lid ring (2) having a longitudinal axis (L2) and a circumferential wall (3) extending in the direction of the longitudinal axis (L2) and having an inner surface (3A) and an outer surface (3B) as well as a first end (3C) and a second end (3D), wherein the lid disk (1) and the lid ring (2) are joined to one another in a materially bonded manner, characterized in that the lid disk (1) has a flat region (1.1) extending transversely with respect to the longitudinal axis (L2), and has, on its outer circumference, a U-shaped region (1.2) adjoining the flat region and having a first wall section (1.3) and a second wall section (1.4) which are connected to one another via a third wall section (1.5), and wherein the lid ring (2) engages with its first end (3C) in the U-shaped region (1.2) of the lid disk (1) in such a way that the first wall section (1.3) rests against the inner surface (3A) and the second wall section (1.4) rests against the outer surface (3B), and in that the first wall section (1.3) and the second wall section (1.4) of the U-shaped region (1.2) of the lid disk are connected to the first end (3 c) of the lid ring (2) by a material bond.
 2. The lid according to claim 1, characterized in that the wall (3) is retracted inwardly in the direction of the longitudinal axis (L2) in its region that engages in the U-shaped region (1.2) of the lid disk (1), thereby forming a shoulder (3.1) below the lid disk.
 3. The lid according to claim 1, characterized in that the outer diameter (D1) of the lid disk (1) is smaller than the inner diameter (d3) of the wall (3) of the lid ring (2) in the region of the second end 3D.
 4. The lid according to claim 1, characterized in that it is stackable, wherein the inner diameter (d3) of a lid (D) engages over the outer diameter (D1) of a lid (D) located below it and the second end (3C) rests on the shoulder (3.1) of the lid (D) located below it.
 5. A method for producing a lid (D) according to claim 1, characterized in that first a pre-drawn conical lid disk (2) is produced, which has an edge region (4) and a flat region (1.1) which is offset thereto by a conical shoulder (5), in that a lid ring (2) with a first end (3C) of a wall (3) is positioned at the outer circumference of the conical shoulder (5) or inside the conical shoulder (5), and in that subsequently at least a portion of the conical shoulder (5) is formed against an inner surface 3A and the edge region (4) is formed against an outer surface (3B) of the wall (3) of the lid ring (1) and sealed thereto.
 6. The method according to claim 5, characterized in that the wall (3) of the lid ring (1) is retracted in the direction of the longitudinal axis (A) of the lid ring (1) when connecting to the lid disk (2), or in that the wall of the lid ring (1) is retracted in the direction of the longitudinal axis (A) at a first end (3 c) before or after connecting to the lid disk (2). 